Platelet Function Decreases with Increasing Severity of Liver Cirrhosis and Portal Hypertension—A Prospective Study

Background Cirrhotic patients display an increased risk for both bleeding and thrombosis. We investigated platelet activation across Child–Pugh stages (CPSs) and portal hypertension (PH) severity. Material and Methods A total of 110 cirrhotic patients were prospectively included. CPS and hepatic venous pressure gradient (HVPG) were determined. Platelet surface expression of P-selectin and activated glycoprotein (GP) IIb/IIIa were measured by flow cytometry before/after stimulation with protease-activated receptor (PAR)-1 (thrombin receptor activating peptide, TRAP) and PAR-4 (AYPGKF) agonists, epinephrine, and lipopolysaccharide (LPS). Results Platelet count was similar across CPS but lower with increasing PH severity. Expression of P-selectin and activated GPIIb/IIIa in response to TRAP and AYPGKF was significantly reduced in platelets of CPS-B/C versus CPS-A patients (all p < 0.05). Platelet P-selectin expression upon epinephrine and LPS stimulation was reduced in CPS-C patients, while activated GPIIb/IIIa in response to these agonists was lower in CPS-B/C (all p < 0.05). Regarding PH severity, P-selectin and activated GPIIb/IIIa in response to AYPGKF were lower in HVPG ≥20 mmHg patients (both p < 0.001 vs. HVPG < 10 mmHg). Similarly, activated GPIIb/IIIa was lower in HVPG ≥20 mmHg patients after TRAP stimulation (p < 0.01 vs. HVPG < 10 mmHg). The lower platelet surface expression of P-selectin and activated GPIIb/IIIa upon stimulation of thrombin receptors (PAR-1/PAR-4) in CPS-B/C and HVPG ≥20 mmHg patients was paralleled by reduced antithrombin-III levels in those patients (all p < 0.05). Overall, PAR-1- and PAR-4-mediated platelet activation correlated with antithrombin-III levels (p < 0.001). Conclusion Platelet responsiveness decreases with increasing severity of liver cirrhosis and PH but is potentially counterbalanced by lower antithrombin-III levels.